质子交换LiNbO3光波导的特性研究

采用X射线衍射谱法和红外吸收光谱法对质子交换和退火质子交换LiNbO3光波导的特性进行了研究.研究结果表明:在LiNbO3晶体衬底X射线衍射主峰的左侧出现质子交换LiNbO3光波导的伴峰,则质子交换使光波导层Li1-xHxNbO3的晶格常数比衬底的晶格常数稍大,产生垂直于表面的应变,波导经过退火后,伴峰向主峰靠近,应变减少.质子交换波导中的OH-基团的红外吸收光谱在3 500和3 300 cm-1处存在特征峰,波导经过退火后,3 300 cm-1处的特征峰基本消失,而3 500 cm-1处的吸收强度基本不变.实验还表明,OH-在3 500 cm-1处吸收带的积分面积基本与交换时间的开方呈正比例关系.

Studies on Characteristics of Proton-Exchanged LiNbO3 Optical Waveguides by X-Ray Diffraction and Infrared Absorption Spectroscopy

The characteristics of proton-exchanged and annealed proton-exchanged LiNbO_3 optical waveguides were studied by(X-ray) diffraction and infrared absorption spectroscopy.The X-ray diffraction experiments show that there are diffraction peaks of Li_(1-x)H_xNbO_3 on the left of the main peak of the LiNbO_3 crystal substrate.This result means that the crystal lattice constant of the layer Li_(1-x)H_xNbO_3 is little larger than that of the LiNbO_3 crystal substrate,resulting in a stress.After annealing,the X-ray diffraction peaks of the waveguide layer move towards the main peak of the LiNbO_3 crystal substrate,and the stress decreases.The infrared absorption spectroscopy experiments show that there are absorption peaks of OH~-at 3 500 and 3 300 cm~(-1),and after annealing,the intensity of the absorption peak at 3 300 cm~(-1) decreases or disappears,while the intensity of the absorption at 3 500 cm~(-1) remains almost invariable.Experiments also show that the integral area of the absorption at 3 500 cm~(-1) is proportional to t_e.